Hi!
Thanks for your post and sorry for the trouble!
Unfortunately, that won’t work like that. For this, I recommend working with hidden rows/columns, which can then be used to separate the calculation from the display:
In one row, hidden to the user, use “normal” cell values, without decimals, formatting, etc.
Then, in e.g. the next row (which will be visible), only do =number_format_eu(A2) etc. to format that cell.
Best wishes,
Tobias